Had a reply on the kickstarter site, looking forward to trying it myself tonight on the Rytm and A4:
It’s not going to be a problem. What we found was that a lot of devices had “peaky” current draw, usually a high inrush current (as the device boots up).
When we say 9W, we mean that we’ve tested ripcord outputting 9W for 8 hours, without any adverse problems, no overheating, or any variation in output voltage.
We engineered it so it’s comfortable at that. It will also handle current draw peaks of up to 16W. So we’re speccing on the safe side.
Very few handheld musical devices will need more than that.
In terms of device protection, we think it is well covered, any decent device requiring over 16W will be engineered to be able to deal with power outs, even if it’s just reverting to reset.